Laying the foundations of the structures in principal, means installation into the earth one or more kinds of different substances and/or materials in order to supplement or replace the existing soil, which itself does not satisfy the loading requirements for such structures. The substances and materials can react with or connect with the ground mechanically, chemically or both.
The introduction of the material into the earth depend on the technique which can be performed by the piling apparatus without replacing the ground, such as methods of piling or pressing the materials, or with replacing the ground such as drilling, scrapping, digging, etc. In both two cases, the replacement and the addition of the ground is always carried out by the assistance of the external forces, originated from diesel, petroleum or electric engines and therefore a counterbalance is always required to balance those forces. The counterbalance may be the apparatus' weight, the loads on it, or the friction with the ground. Those processes always result in a certain mechanical output, represented by the ratio of the minimum required energy to the actual energy of the specific apparatus and/or technique employed. When using those processes, one should consider those factors such as environmental influence, the complicatedness of the operation, the viality stability, cost-effectiveness, etc.
Among the currently existing technologies that have been used for pressing a certain material against the ground, such as các loi concrete piles, stainless steel, wooden, loose material such as sand, stone, soft material such as plastic pipe, absorbable rush, one of the popular methods is to use a counterbalance, usually the device's weight or the concrete blocks in order to balance the pressing force, the method has the following disadvantages:                It requires a certain counterbalance as huge concrete blocks and therefore the transportation cost is large.        It requires an appropriate construction site so that counterbalance blocks have not sunk or slanted.        In many cases, the construction site's limitations such as the proximity to housing areas, weak ground-base, offshore construction or size limitations of counterbalance resulted in the impossible construction.        The pressing material directly against the ground occupies the construction area and therefore may risk the neighborhood's foundations.        The use of a single unique material from top to the bottom shall limit the effectiveness of different kinds of material.        
The followings are some popular applications of foundation pilings of the engineering and constructions structures:
1. Filling-Drilling Piles
Filling-drilling piles are indepth foundations sâu, are currently widely used as foundations for structures such as skyscrapers, bridges, seaports, plants, etc., and gradually are replaced for other foundations such as driving piles.
Filling-drilling piles are widely applied because of the following advantages:                The central load-bearing ability is high: due to the filling-drilling piles' sizes are usually bigger than other piles, the load-bearing ability of the filling-drilling piles may be a several ten times higher than the load-bearing ability of other piles.        The construction with the filling-drilling piles is less noisy, less vibrating, especially when compared with driving piles.        It is possible to drill into hard rock, where other kinds of piles cannot be implemented.        
However, besides the above advantages, the filling-drilling piles also have some disadvantages as the followings:                The ability to control the viality is low.        The cost is high.        It is environmentally polluted when using the common drilling methods with drilling solutions.        It produces a large amount of waste dirts.        It requires a huge amount of fresh concrete, resulting in demands for the in-site fresh concrete supply as well as the control of the concrete viality.        
2. Pressing Piles
Pressing piles are pre-cast piles composed of different materials such as reinforced concrete, stainless steel, wood, or combination thereof.
Pressing piles are inserted based on the principle of using certain required pressing force, together with the necessary counterbalance formed by heavy blocks or by anchoring to the ground, which presses on one end of the pile or on the pile body.
The construction of pressing piles by pressing has the following advantages:                Cost-effective.        No noise is produced.        No pollution is produced.        
However, the construction of pressing piles by pressing also has the following disadvantages:                The central load-bearing ability is low.        The horizontal load-bearing ability is low.        A large construction area is occupied. It is difficult to insert piles at narrow angles or small construction site.        The pressing piles shall occupy some rooms under the ground resulting in possible breakage or sink of the neighborhood's strictures when applying the high-density pressing.        